SIC Trend

The trend of high voltage and high current for electric vehicles remains unchanged,

and SiC will become the key material for the realization of technology

Compared with traditional cars, motor vehicles mainly have more batteries, motors, inverters and converters, and replace traditional mechanical drives with electric control (Semiconductors are required). Therefore, the demand for semiconductors in electric vehicles has increased sharply compared with traditional fuel vehicles. .

At present, the current of electric vehicles on the market is mostly 200~240A, and the voltage is 300~400V. However, it is judged that as consumers’ requirements for vehicle performance and fast charging increase, moving towards high current and high voltage is an inevitable development strategy for car manufacturers. . For example, the latest rated standard voltage of Bidi has exceeded 600V, while that of Porsche and Taycan is 800V, not to mention charging piles that are often over 1000V to achieve fast charging. The key to achieving high voltage and high current lies in the above-mentioned semiconductor components. Therefore, automotive semiconductors are the next key to competition among automakers.

At present, most automotive semiconductors use Si MOSFETs in the environment above 600V, and IGBTs (insulated bars and bipolar transistors, readers can simply think of them as semiconductors that can withstand high voltages) above 600V, while SiC is used in Tesla and Model 3. Later, it was imported by more and more car manufacturers.

Compared with IGBT, SiC does not generate tail current, so it can reduce switching loss by nearly 90% (theoretically, in order to reduce resistance, IGBT will perform conductivity modulation and inject holes as minority carriers into the drift layer, but in doing so At the same time, it will also cause the accumulation of minority carriers, which will generate a tail current when it is turned off, resulting in a large switching loss).

In addition, the breakdown voltage of SiC (Breakdown Voltage is 10 times that of Si, so in addition to being able to withstand high voltages above 1000V, it can also reduce the amount of passive components for resistors and capacitors, thereby reducing the overall part volume. For example, in a 900V environment, SiC-MOSFET The chip size only needs 3% of Si-MOSFT, and 10% of Sj-MOSFET can achieve the same on-resistance; another example is the SiC inverter module developed by Japan Rohm Semiconductor, which is 43% smaller than IGBT and lighter in weight 6 kg.

In addition, the IGBT inverter cannot withstand high temperatures, so it must be installed separately from the motor, and then connected with the control line; however, the Sic can be directly packaged with the motor to further increase performance. Therefore, judging from the current evidence, the introduction of SiC has significantly improved the acceleration, battery life, and charging efficiency of electric vehicles. It is judged that under the characteristics of performance upgrades in consumer electronics products, it is inevitable that electric vehicles will adopt SiC in large numbers in the future. The IGBT acts as a transitional element before SiC is popularized.


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